Commit-ID: de5077c4e38f2a51f50d28bdd5e4a0f14b3d16ff Gitweb: http://git.kernel.org/tip/de5077c4e38f2a51f50d28bdd5e4a0f14b3d16ff Author: Andi Kleen <[email protected]> AuthorDate: Fri, 11 Aug 2017 16:26:22 -0700 Committer: Arnaldo Carvalho de Melo <[email protected]> CommitDate: Tue, 22 Aug 2017 12:09:04 -0300
perf tools: Add utility function to detect SMT status Add an smt_on() function to return if SMT is enabled or disabled. Used in the next patch. Signed-off-by: Andi Kleen <[email protected]> Acked-by: Jiri Olsa <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Arnaldo Carvalho de Melo <[email protected]> --- tools/perf/util/Build | 1 + tools/perf/util/smt.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ tools/perf/util/smt.h | 6 ++++++ 3 files changed, 51 insertions(+) diff --git a/tools/perf/util/Build b/tools/perf/util/Build index 8d49a98..94518c1 100644 --- a/tools/perf/util/Build +++ b/tools/perf/util/Build @@ -22,6 +22,7 @@ libperf-y += rbtree.o libperf-y += libstring.o libperf-y += bitmap.o libperf-y += hweight.o +libperf-y += smt.o libperf-y += quote.o libperf-y += strbuf.o libperf-y += string.o diff --git a/tools/perf/util/smt.c b/tools/perf/util/smt.c new file mode 100644 index 0000000..453f6f6 --- /dev/null +++ b/tools/perf/util/smt.c @@ -0,0 +1,44 @@ +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <linux/bitops.h> +#include "api/fs/fs.h" +#include "smt.h" + +int smt_on(void) +{ + static bool cached; + static int cached_result; + int cpu; + int ncpu; + + if (cached) + return cached_result; + + ncpu = sysconf(_SC_NPROCESSORS_CONF); + for (cpu = 0; cpu < ncpu; cpu++) { + unsigned long long siblings; + char *str; + size_t strlen; + char fn[256]; + + snprintf(fn, sizeof fn, + "devices/system/cpu/cpu%d/topology/thread_siblings", + cpu); + if (sysfs__read_str(fn, &str, &strlen) < 0) + continue; + /* Entry is hex, but does not have 0x, so need custom parser */ + siblings = strtoull(str, NULL, 16); + free(str); + if (hweight64(siblings) > 1) { + cached_result = 1; + cached = true; + break; + } + } + if (!cached) { + cached_result = 0; + cached = true; + } + return cached_result; +} diff --git a/tools/perf/util/smt.h b/tools/perf/util/smt.h new file mode 100644 index 0000000..b8414b7 --- /dev/null +++ b/tools/perf/util/smt.h @@ -0,0 +1,6 @@ +#ifndef SMT_H +#define SMT_H 1 + +int smt_on(void); + +#endif
